A wavelength division multiplexing network constitutes a basic physical layer of a communications network. As an important indicator of health of the wavelength division multiplexing network, optical performance of a wavelength channel is particularly important for design and maintenance of the wavelength division multiplexing network.
For an established wavelength channel, optical performance can be directly monitored at a node which the established wavelength channel passes through; but for an unestablished wavelength channel, optical performance also needs to be monitored, so as to ensure that after being established, the wavelength channel can satisfy a performance requirement of service subscription.
In the prior art, an external light source provides an optical signal for an unestablished wavelength channel, a virtual wavelength channel is established, and then optical performance is monitored at a node which the virtual wavelength channel passes through. However, in this method, the external light source brings about complexity and additional monitoring costs. Besides, an operating parameter of the external light source needs to be manually adjusted and therefore reliability is low, and dynamic monitoring of optical performance cannot be implemented.